An ophthalmologic apparatus is a device that is usable in the ophthalmologic field. In the ophthalmologic field, tests or examinations are classified into objective ones and subjective ones.
Through an objective test, information related to a subject's eye is obtained mainly by a physical method without reference to a response from the subject (see patent documents 1 and 2). The objective test includes an objective measurement for measuring a value related to the subject's eye, imaging for acquiring an image of the subject's eye, and the like. Typical examples of the objective test include objective refractivity measurement, corneal shape measurement, intraocular pressure measurement, fundus photographing, and optical coherence tomography (OCT).
On the other hand, through a subjective test, the result is obtained based on a response from the subject (see patent documents 1 and 2). Typical examples of the subjective test include visual field test and subjective refractivity measurement such as far vision test, near vision test, contrast test, and glare test. In the subjective test, information (visual targets or optotypes, etc.) is presented to a subject, and the result is obtained based on a response to the information from the subject. For example, tests such as a far vision test and a near vision test are conducted using a measurement value obtained by an objective measurement. The far vision test is used to obtain the far visual acuity of the subject's eye and the far sight power of a prescribed lens using optotypes arranged spatially or optically at a first distance (e.g., 5 meters, 6 meters, 20 feet, etc.). The near vision test is used to obtain the near visual acuity of the subject's eye and the near sight power (additional power) of a prescribed lens using optotypes arranged spatially or optically at a second distance (shorter than the first distance, e.g., 30 centimeters, 40 centimeters, etc.). The contrast test is conducted as the contrast of presented visual targets is being changed (or using a stripe visual target, etc.) to obtain the spatial frequency characteristics (contrast sensitivity) of a visual system including the subject's eye. The glare test is applied to the case where opacity occurs in intermediate optic media as in the cataract and corneal clouding, a follow-up after corneal refractive surgery, and the like. The glare test is conducted by presenting a visual target illuminated by a background light (glare light source) to obtain the influence of a reduction in the contrast of a retinal image due to scattering of light caused by an opacity or the like (difficulty with glare).